Hot beverage dispensers, i.e. apparatus for the extraction of a substance for the production of a preferably hot beverage, are known in the prior art. Thus, for instance, the EP 512 470 B1, the U.S. Pat. No. 7,347,138 B2 or the DE 20 2008 014 U1 disclose this type of apparatus for the extraction of sealed beverage capsules.
The substance contained in the dimensionally stable, closed capsules made of plastic, metal or plastic and metal is either powdered or fluid. The substance may be, by way of example, roasted or ground coffee, soluble coffee, a mixture of ground and soluble coffee, tea, a chocolate or milk product or any other dehydrated and consumable substance.
In the generic hot beverage dispenser a beverage capsule is first placed in a receptacle, then a brewing chamber comprising a base plate and lid is locked and finally the beverage preparation substance is extracted, preferably with hot water.
In this process the brewing chamber is fed with heated water or steam, as the case may be, for instance via the base plate, which then flows through the beverage preparation substance in the capsule or dissolves it. During the flowing through or dissolving of the beverage preparation substance, a desired pressure of up to 10 bar can build up inside the brewing chamber and therefore in the beverage capsule. A high pressure is advantageous especially in the extraction of ground coffee. However this harbours the risk that the glued, welded or flanged beverage capsule may burst open at certain weak points.
This bursting of the capsule can be seen in particular when there is no fully form-fitting connection between the base plate and the lid of the brewing head.